This pertains to everybodies favorite, high end, exterior wall covering, vinyl siding. OK. That said. Those who remain and have not punched out their monitor can hear the question.
It looks like I got trapped into helping with a vinyl siding project. Charity project. I got talking to the guy I’m going to be working with and asked a dumb question. He described the installation. Tar paper. Tack up fan fold and snap lines. Then the siding.
Out of ignorance I asked if the fan fold would be better under the tar paper. The guy looks at me and admitted that he had always done it insulation over tar paper but that under the tar paper sounded OK also. He said it would make snapping lines easier but didn’t know for sure.
Does anyone have any thoughts on the subject. Which way is “right”, customary normal? Why? Advantages? Disadvantages? Wild raving, foaming at the mouth diatribes and any thoughtfully considered opinions welcome.
Replies
Most of what I have done has been siding over existing clapboard so we just stapled up the fan fold over the old siding. On a new siding job over OSB or plywood sheating, i think I would follow your lead and but the insulation under the tar paper. Of course I haven't done a siding job in about 8 years, so don't have clue really.
Dave
I have done a few siding jobs with vinyl. I thought fan fold was mainly marketed as levelor for vinyl over clapboard situations. No one I know in my area uses it on a new construction install. If fanfold is being used as a levelor then no paper or house wrap is used. So I guess I simply have never heard of or seen the two used together. DanT
I'm with DanT - Never seen or heard of using it in new construction. Don't see that the minimal R value would make it worthwhile.
Doctors can be frustrating. You wait a month-and-a-half for an appointment, and he says, "I wish you'd come to me sooner."
This raises a very good point.
Maybe the vinyl should go behind the paper. We all know the paper is more water tight than vinyl.
The fanfold should be applied over the felt. The paper is a much better moisture barrier than the fanfold, so it should go against the house. Do NOT tape the seams on the fanfold! this would make a double vapor barrier (fanfold isn't breathable) and could cause possible mold/rot issues. You shouldn't need fanfold on a new construction project, but if they truly want it, cut it a little short and use it only as a leveling board. Let the felt do it's thing and that fanfold will level out any inconsistancied in the wall.
Ok dumb question. If you use foamboard (impermeable sheets) on the exterior is Tyvek or house wrap even necessary?
I agree the foamboard is not a breathing layer but it is pretty standard practice. So am I missing something? It seems like an indictment of the foam board or fan fold.
Jack of all trades and master of none - you got a problem with that?
Fan fold has one purpose. Leveling out walls that you are not taking the old siding off of. The R value is 1.5. I would use one or the other. With vinyl it would be fan fold. Tar paper is for wood siding. Both seems overkill.